CYLINDER HEAD REMOVAL to INVESTIGATE SUDDEN HIGH COMPRESSION PROBLEM

ANLAF

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The kickstarter used to be a smooth action - now I am on the point of opening up thetop end to see of the problem is in there.

BACKGROUND - when I got it the bike sounded like that old cartoon bike in Aristocats (if the have children, you'll know what I mean), bagging away as if it was firing on both cylinders at the same time, wanting to be a single - an what do you know, the wires from the coils went into a single wire then headed out to the points. It was doing the old TINGLE after all. Come to think of it, the bike stopped if I removed the right cylinder suppressor cap (I think the problem lies on the right side - read on!).

Everything was fine, then I lost neutral, 1st, 2nd and 3rd gears. I have just finished solving the gears problem (replaced damaged shifter-shaft, made the correct adjustments, put in new clutch plates and springs, and made sure there was nothing that might affect the kickstarter mechanism). I have redone the wiring, and adjusted (in the recommended order) the cam chain adjuster, the valves clearances, then put in Boyer ignition. When I went to start the bike something had changed - the kickstarter smooth action had transformed overnight into a wild beast. Now, I am not small, 220lbs (okay, 235lbs) and there wss no way I could budge the thing without using all my force (the little darling chatted back and nearly broke something bone-like, and left a 1/4 inch reminder of who's boss imprinted in the back of my leg).

I got the bike running when I thought it wasn't looking. The carbs were slightly out of adjustment (you might have seen the thread about butterfly valve synchronisation) which might have contributed to backfiring through the carburettor, but the problem is a bit more systemic than that.

Plugs out, fine. The valve action feels good. Plugs in (ignition off), and there we have it - back to square one (so the carbs are eliminated). It was running rich on the right cylinder (I put that down to the carb mal-adjustment) but there is quite a good deal of carbon in there (looking through the spark plug hole and in the exhaust outlet). I put a small brush in the right cylinder via the exhaust valve just in case there was something blocking the valves seating correctly - nothing, just powdery blackness, nothing that might have held open a valve.

As I see it, the only thing I have changed that might affect the kickstarter so much is adjust the cam chain to spec (it was popping out 1/4" and staying out about an 1/8"). This suggests the chain was much too tight, and I put it to spec; then the valves 0.06mm and 0.15mm (I think the inlets had been set a little wider, 0.07 or 0.08; then I put in the Boyer.

If anyone has an idea of the cause I would be grateful, otherwise it strikes me the sensible thing to do would be to take the cylinder assembly off, check that cam chain and mechanism, and give the valves etc a clean.

Any suggestions greatfully received.

Anlaf
 
If you disturbed or removed the kick start assembly when you had that right cover off, it may not be installed properly.
 
Thanks 5twins, but absolutely not. I read as much as possible before touching the right hand side and made particular note on not disturbing the kickstarter mechanism.

Just to be clear, the kickstarter/compression problem was there before I opened the rightside cover. I daren't breath on that exposed kickstarter mechanism when it was exposed. The only time I went near it was to replace the washer that sits behind the rightside cover.

I am thinking it will be a combination of worn cam chain and ill-seated valves.

Anlaf
 
Yes, SteveH, I have double triple and quadruple checked the cam chain and valves -and I will go carefully through the whole process again today. When I came to adjust the cam/valves/timing for the first time (until then all was fine with the kickstarter action) I noticed the cam chain adjuster pin was set as if it held the chain too tight (with the pin set out about 1/4", and returning but still staying out about 1/8") - that was holding the chain way to tight (unless of course the cam chain spring is not doing its job, or the cam chain itself is stretched.

I read the descriptions of the various types of cam chain tensioners by inxs, and mine is Type D (see the photo). Inxs says that a tight chain will affect valve timings - that sounds promising to me. My valves are set correctly (following the step-by-step the video recommended in the threads).

Anlaf
 

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Two Many, with the spark plugs out the action is smooth, I hear the valves opening and closing. I wondered if something might have got into the cylinder hear through the spark plug hole while I have been working on the bike - well it has been running since then so it can't be anything huge and metalic, but could a tiny fragment of something have got in there and stopping a valve?

Some kicks judder as they go down, others seem to lock halfway, but all kicks will go if I put my weight through it - it all points to valves not opening in the sequence they should. That is the result, I need the cause. The kickstart mechanism has no sign of damage and has not been disturbed (before or after the problem began).

Anlaf
 
Anlaf, if the kickstart action is smooth with the sparkplugs removed, then you have no mechanical interference issues with the valves, and the kickstart mechanism is fine. What SteveH was suggesting is for you to check the IGNITION timing. It is likely that the spark timing may be too advanced, resulting in premature kickback...
 
COULD IT BE IGNITION TIMING? - SteveH thinks it might be, so lets look at that. It was running fine (everything is relative) with points. Then the adjustments. Then I put in Boyer ignition. I called Boyer and asked them if their timing setting at the FULL ADVANCE of 38 degrees could be linked to my problem - they said no!

I will check that timing mark anyway today again, in order - cam chain tensioner, valves, ignition, then carbs. Thanks for the help fellers, keep it coming. I am not there yet.

Anlaf
 
You'll want your full advance timing at 38°, when the engine is running past 3000 rpm, best checked with a timing light. BUT, for idle, the ignition timing should be in the area of 13-17° BTDC. If it's at 38° while kickstarting, best update your medical insurance...
 
At the moment I am not trying to start the bike, just going through the whole cam chain tensioner adjustment (done) and valves (done). Still (with plugs out) smooth action and valves opening and closing. With plugs in back to the extraordinary judder/locking feel to the kickstarter.

Unless there is something I've missed, I can only imagine something is not working well with the cam chain and valves. Unless anyone has any suggestions, it looks like I'll take of the cylinder head and see what I can find.

Anlaf
 
if the timing has been checked correct then the only other thing I can think of is that your advance is out of adjustment giving you too much advance when starting .Which Boyer do you have is it the one with the electronic advance ? or do you still have the mechanical fitted /

If all else fails try reversing everything you did and set everything back to where it was . then adjust one thing at a time until you find the culpret.

If it turns over smoothly with the plugs out it has to be timing related .
 
Do not remove the head. You do NOT have too much compression or anything "blocking the valves". how does it kick over with the ignition OFF?
 
Peanut, this problem was there before I tried to start up after maintenance.

I installed Boyer ignition Micro-Power, Kit 303.

I followed their instructions to the letter, and lined up the timing dot with the advanced timing mark (extreme left on the timing plate. I have a strobe light to make adjustments when it is running and warm (idle and at higher revs), but that is to come. They said installing their system would have no effect whatsoever on the mechanical side (my problem).

I have just completed three runs of adjustment: I backed-off the valve adjustments beofre I started, then did the cam chain, then reset and checked again the valve gaps to 0.15mm and 0.06mm. Plugs out fine, plugs in, ouch!

Is there anything at all I have missed?

NOTE The cam chain adjustment is in the flush position; I used the timing mark to the right of the T on the timing plate to set the valves (I believe that is TDC). And the Boyer to the full advance at 38 degrees.

Anlaf
 
gggGary, kick-over with ignition off is smooth, and I hear the gentle clunking of the valves. Kickstart returns. No other noise, e.g. any cam chain rattle.

This is a mystery. I have dismantled as far as my socket wrench waiting on the cylinder bolts.

Anlaf
 
Thanks, gggGary. In that case, what I think it best to do is put it together, get the bike started, let it warm up, then go through the whole adjustment procedure again including putting the strobe to the timing marks.

Well, here goes - and TwoMany, yes, I'll check the medicine insurance.

Anlaf
 
I've just looked on the Boyer branson website and the Micro Power electronic kit you have fitted does control the advance and retard electronically .

It sounds to me like the Boyer unit is giving you too much advance at start up which is why you are having problems with kick back. Its trying to start with the spark way too far advanced .

Is the Boyer unit manually adjustable or fixed?

http://www.boyerbransden.com/microdigitalmicropower.html
 
Peanut, I have just put everything back together and as soon as this cup of tea is finished I will be going out there to start - I don't have a PMA yet (next on the list) so what do you know, the battery was below the output it needed to start the thing.

By the way, what PMA is recmmended?

Anlaf
 
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